(a) The distance to a star is approximately 5.80 1018 m. If this star were to bu

Question

(a) The distance to a star is approximately 5.80 1018 m. If this star were to burn out today, in how many years would we see it disappear? 1 years (b) How long does it take for sunlight to reach Mercury? 2 minutes (c) How long does it take for a microwave radar signal to travel from Earth to the Moon and back? 3 s (d) How long does it take for a radio wave to travel once around the Earth in a great circle, close to the planet's surface? 4 s (e) How long does it take for light to reach you from a lightning stroke 10.1 km away? 5 s

Explanation / Answer

Using

V=d/t. The speed of light, c is 3e8 m/s.

a) V = d/t

3e8 m/s = 5.80e18 m / t

t = 1.9333e10 sec = 613.056 years

b) distance from sun to mercury = 57.91*10^9 m

v=d/t

t = 200s = 3.32 min

c) distance from Earth to moon is 3.84e8 m

v=d/t

3e8 m/s =2*3.84e8 m / t

t = 2.56 s

d) We need the circumference of Earth, using 2r. The radius of Earth is 6.38e6 m, so

C = 2r

C = 2(6.38e6 m) = 4.01e7 m. Now, we use:

v=d/t

3e8 m/s =3.99e7 m / t

t = 0.1332 sec

e) d = 10100 m, so:

v=d/t

3e8 m/s = 10100 m / t

t = 3.367e-5 sec

Related Questions

Navigate

• Browse (All)
• Browse #
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.